Retune my entire carb after installing new heads?

Thanks... I am not surprised that jetting is likely to change, along with main air bleeds, since the new heads allow a lot more air in to make more horsepower :)

But as I asked initially, with the throttles closed except for idle air, I would not have thought that the (maximum) head flow would have an effect, since the throttles are the major limiting factor at idle.

Anyway, Bewy theorized that the increased port volume is changing the carb signal at idle too - made sense to me.

Edited to add: no, it does not ping at tip-in even on a hot day. I am conservative with ignition timing (and a good accelerator pump squirt).

Also to add: Dwayne tells me his dyno mule carbs work well within limited hp ranges and gave examples such as: 750 good for 400-550 hp combos but lean on 550-600 hp. And I did transition from the first group to the second with the heads :D